Unconventional sign-changing superconductivity near quantum criticality in YFe${}_2$Ge${}_2$

Abstract

I present the results of first principles calculations of the electronic structure and magnetic interactions for the recently discovered superconductor YFe${}_2$Ge${}_2$ and use them to identify the nature of superconductivity and quantum criticality in this compound. I find that the Fe $3d$ derived states near the Fermi level show a rich structure with the presence of both linearly dispersive and heavy bands. The Fermi surface exhibits nesting between hole and electron sheets that manifests as a peak in the susceptibility at $(1/2,1/2)$. I propose that the superconductivity in this compound is mediated by antiferromagnetic spin fluctuations associated with this peak resulting in a $s_{\pm }$ state similar to the previously discovered iron-based superconductors. I also find that various magnetic orderings are almost degenerate in energy, which indicates that the proximity to quantum criticality is due to competing magnetic interactions.

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Cited by in corpus (18)

• Unconventional superconductivity in the layered iron germanide YFe${}_2$Ge${}_2$
• Fermi liquid breakdown and evidence for superconductivity in YFe${}_2$Ge${}_2$
• Superconductivity and Magnetism in YFe${}_2$Ge${}_2$
• Spectroscopic Evidence for Strong Quantum Spin Fluctuations with Itinerant Character in YFe2Ge2
• Crystal growth and annealing study of fragile, non-bulk superconductivity in YFe${}_2$Ge${}_2$
• Non-trivial role of interlayer cation states in iron-based superconductors
• Magnetism in Na-filled Fe-based skutterudites
• Unconventional bulk superconductivity in YFe${}_2$Ge${}_2$ single crystals
• Coexistence of ferromagnetic and stripe-type antiferromagnetic spin fluctuations in YFe${}_2$Ge${}_2$
• Approaching itinerant magnetic quantum criticality through a Hund's coupling induced electronic crossover in the YFe${}_2$Ge${}_2$ superconductor
• Unraveling the origin of Kondo-like behavior in the 3$d$-electron heavy-fermion compound YFe${}_2$Ge${}_2$
• Fermi surface and mass renormalization in the iron-based superconductor YFe${}_2$Ge${}_2$
• Composition dependence of bulk superconductivity in YFe2Ge2
• Itinerant magnetism in metallic CuFe2Ge2
• Evidence for proximity of YFe${}_2$Si${}_2$ to a magnetic quantum critical point
• Nearly ferromagnetic metal state in the collapsed tetragonal phase of YFe${}_2$(Ge,Si)${}_2$
• On magnetic structure of CuFe2Ge2: constrains from the 57Fe Mossbauer spectroscopy
• Magnetic competition in iron-based germanide and silicide superconductors